This invention comprises a composition for dyeing of human hair providing superior stability and simultaneously a hair coloration with improved coloring intensity.
It is generally known that hair dyeing compositions are classified into two categories, i.e., on the one hand permanent dyeing compositions comprising oxidizing hair dye-stuff precursors, which, together with oxidizing agents, develop the desired hair coloration depending on the formula chosen; and, on the other hand, semipermanent hair dyeing compositions comprising direct dyes which do not require any addition of an oxidizing agent to develop their dyeing effect. Accordingly, these dyeing results are less permanent than those obtained with permanent dyeing compositions.
These dyeing compositions on the basis of direct dyes are usually applied either as tinting shampoos, lotions or color setting lotions, optionally also as aerosol foam preparations.
The direct dyes used therein are normally of the cationic type; rinsing compositions also contain cationic surfactants, particularly quaternary ammonium salts, as additional essential ingredients.
The dyeing intensity and permanence achieved with these compositions is, however, not always satisfactory. A possibility for improvement of light fastness is the addition of UV-absorbers to the hair dyeing compositions to protect the hair from light damaging.
The water-insoluble UV-absorbers normally used for this purpose, however, are not suitable in this respect, as they do not adhere to the hair substantially.
Water-soluble UV-absorbers with anionic groups are known per se. Due to their substantivity they are generally suitable to improve the light fastness of hair treated with dyes containing direct-acting dyestuffs.
However, it has not been possible to incorporate these water-soluble UV-absorbing, anionic groups containing compounds into usual cationic direct-acting hair dyestuff compositions, as obviously an interaction took place between the two substances leading to an instable composition.